In recent years, IC cards and electronic devices such as mobile phones are required to be thin in thickness, compact in size, and light in weight. In order to meet the requirements, semiconductor chips that are incorporated have to be thin in thickness as well. Accordingly, it is said that wafer substrates for next-generation chips have to have a thickness of 25 μm to 50 μm although wafer substrates forming the basis of semiconductor chips currently in use have a thickness (film thickness) of 125 μm to 150 μm. As such, processes for reducing the thickness of the wafer substrates are essential to obtain the wafer substrates having the above-described film thickness.
Because the strength of a wafer substrate is decreased by a thinning process, structures such as a circuit are mounted on the wafer substrate while the wafer substrate is automatically transported in a state where a support plate is adhered thereto during a manufacturing process so as to prevent damage to the thinned wafer substrate. After the manufacturing process, the wafer substrate is separated from the support plate. Accordingly, it is preferable that the wafer substrate and the support plate be firmly adhered to each other during the manufacturing process. However, after the manufacturing process, it is preferable that the wafer substrate be smoothly separated from the support plate.
In a case where the wafer substrate and the support plate are firmly adhered to each other, it is difficult to separate the support plate from the wafer substrate without causing damage to the structures mounted on the wafer substrate depending on adhesive materials. Accordingly, the development of a temporary fixing technology, which is extremely difficult, is required for firm adhesion between the wafer substrate and the support plate during the manufacturing process and separation of the elements mounted on the wafer substrate without damage to the elements after the manufacturing process.
As an example of the temporary fixing technology, a release layer which has a property that changes when irradiated with light may be disposed in advance between an adhesive layer that adheres the wafer substrate and the support plate with each other and the support plate. After the property of the release layer is changed (altered) by irradiating the release layer with light, a force is added to the laminate where the wafer substrate and the support plate are adhered so that the separation between the support plate and the wafer substrate can be performed.
Herein, Patent Literature 1 discloses a peeling apparatus that includes adsorption means where a support plate is adsorbed and peels off the support plate from a substrate to which the support plate is adhered.
Also, Patent Literature 2 discloses a glass substrate peeling apparatus that includes peeling means which peels off a glass substrate adsorbed and held by an adsorption sheet with a liquid being interposed from the adsorption sheet.